Re: reach down
You slow down/stop the child by grabbing him/her by the jacket and ask the parent, essentially, if they are looking for "this" (meaning the child). No, we don't usually refer to children as "this" but it's a little attempt a humor, they way you'd pick up a pen that someone has dropped when you see them patting down their pockets looking for the pen, and say [Are you] looking for this?"
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.